Process for the decalcification sugar beet juice

ABSTRACT

Undesirable cations are removed from sugar juice which has undergone a two-stage carbonation by treating the same with the hydrogen form of a carboxylic type cation exchanger, in a column, at a flowrate of 20-200 resin bedvolumes per hour, at an elevated temperature short of boiling, for a contact time less than 3 minutes, and thereafter realkalizing with magnesium oxide and filtering.

atent [1 1 tlnite States Schoenrock et al.

[ June 3,1975

[ PROCESS FOR THE DECALCIFICATION SUGAR BEET JUICE [75] Inventors:Karlheinz W. R. Schoenrock;

Preston Richey; Hugh G. Rounds, all of Ogden, Utah [73] Assignee: TheAmalgamated Sugar Company,

Ogden, Utah [22] Filed: Feb. 19, 1974 [21] Appl. No.: 443,612

[52] US. Cl 127/46 A; 127/50; 127/55 [51] Int. Cl. C13d 3/02; Cl3d 3/14[58] Field of Search 127/46 R, 46 A, 50, 48,

[56] References Cited UNITED STATES PATENTS 1/1963 Popper 127/50 X12/1973 Nishijima 127/50 X OTHER PUBLICATIONS Sugar Industry Abstracts,Vol. 27, abstract 975 Sugar Industry Abstracts, Vol. 30, abstract 689(1968).

Chemical Abstracts, 69:68438d (1968).

Beet-Sugar Tech., R. A McGinnis, ed. 2nd Edition, 330333, Beet SugarDevelopment Foundation, 1971.

Primary Examiner-Morris O. Wolk Assistant Examiner-Sidney MarantzAttorney, Agent, or FirmPierce, Scheffler & Parker [57] ABSTRACTUndesirable cations are removed from sugar juice which has undergone atwo-stage carbonation by treating the same with the hydrogen form of acarboxylic type cation exchanger, in a column, at a flowrate of 20-200resin bedvolumes per hour, at an elevated temperature short of boiling,for a contact time less than 3 minutes, and thereafter realkalizing withmagnesium oxide and filtering.

5 Claims, 1 Drawing Figure Correlation Between Throughput and EffluentpH for the Treatment of Clarified Sugarbcet Juice by Weak Cation ESeconds, Temperature anger with Carhoxy ic Acid Functionality-ContactTime 20 100 Bedvolumes throughput 200 300 PROCESS FOR THEDECALCIFICATION SUGAR BEET JUICE This invention relates to the sugarrefining art, and is concerned with a process of removing undesirablecationic impurities from sugar beet juice via ion exchange for cationswhich enhance operation, crystallization and extraction of sugar fromsugar beet juice so treated.

In the conventional process the so-called first carbonation of the sugarbeet juice with ensuing separation of the clear liquid from precipitatedand suspended solids is followed by a second carbonation of the clearliquid. This two-stage carbonation is necessary to maximize impurityremoval while minimizing the calcium ion concentration prior to theevaporation step. Under normal conditions, however, the calcium ionconcentration is still excessive after this second carbonation, leadingto fouling and scaling of the evaporator heating surfaces. Such foulingand scaling brings about inefficiency in heat transfer and reduction inequipment capacity.

Additives such as soda ash are commonly used to displace the calcium ionand to cause its precipitation as calcium carbonate according to Formula1:

Ca. An Nazcog Ca CO3 Nag An where An signifies anionic impurities in thesugar beet juice.

Other so-called softening techniques which use a strong, sulfonic typecation exchanger operated over the sodium form have also foundwidespread application in reducing the calcium ion concentration insugar beet juice prior to evaporation.

It is now an established fact that the sodium ion which is commonly usedto displace the calcium ion either in the form of an additive or throughion exchange techniques imparts increasing solubility upon the sucrosehence reduces extraction.

In contrast to the solubility-increasing effect of sodium ions uponsucrose is the salting out or solubilitydecreasing effect of magnesiumions upon sucrose in aqueous solutions.

A process has now been discovered which allows the elimination of thescale-forming calcium ions without the introduction of molasses-formingsodium ions.

In accordance with this invention, second carbonation juice ispercolated through the hydrogen form of a weak cation exchanger at arelatively high flowrate of from about 20 to about 200 bedvolumes perhour and at temperatures as high as 95 C. The contact time for the syrupshould not exceed 3 minutes, but should preferably be held below 1minute to minimize sucrose loss through heterogeneous inversion. Thistreatment removes most of the calcium, and also some potassium andsodium, from the second carbonation juice in exchange for hydrogen ions.

Formulas II and VI relate the chemical reactions occurring:

R(COOH) Ca An R(COO) Ca H An R(COOH) K An R(COO)K H An Ill R(COOH) Na AnR(COO)Na H An R(COOK) Ca An R(COO) CA K An R(COONa) Ca An R(COO) Ca NaAn where R signifies the resin matrix, and

An represents juice anions.

As can be seen from reactions In and IV, this process may also be usedto reduce sucrose extractioninhibiting cations such as sodium andpotassium which are naturally occurring in the sugar beet.

The occurrence of free acid in the sugar beet juice so treated may causethis juice to become undesirably acidic. A cation selected from thealkaline earth metal group but preferably magnesium oxide is added to ajuice so treated to neutralize these free acids in the juice and torestore a pH which is desirable for further treatment throughevaporation and crystallization. Formula VII illustrates this reaction:

H An l- MgO MgAn H O VII After exhaustion of the weak cation exchangerwith calcium ions and sugar beet juice cations the resin is regeneratedwith a suitable acid.

Weak cation exchanger with carboxylic acid functionality such as aredescribed by Ilelferich in Ion Exchange McGraw-Hill Book Co., 1962,pages 30-31 and commercially available under the tradenames of AmberliteRC-50; Amberlite IRC-84; Duolite CC3; Dowex CCR-l; and Lewatit CNP,among others, are suitable for this application. The named exchangerswere used in the following specific examples.

EXAMPLE 1 A sugar beet juice having been defecated via lime and COtreatment followed by a second carbonation being carbonated to minimumcalcium ion concentration in the usual manner and with a pH range of7.5-9.5 and at a temperature between -95 C., being free of suspended andprecipitated solids, is treated with a weak cation exchanger havingcarboxylic acid functionality. A contact time of between 20 seconds and3 minutes depending upon the temperature of the juice is usuallysufficient to reduce the calcium ion concentration in the juice todesirable levels without significant losses of sucrose throughheterogeneous inversion. That is to say, at the high temperature of C. acontact time of less than 1 minute is sufficient and desirable, while attemperatures below 70 C., a contact time of up to three minutes may berequired. The contact time may also be lowered or extended dependingupon the extent of the cation exchange desired. Thus, increasing thecontact time will increase the cation exchange. The treatment of thesugar beet juice with the weak cation exchanger may proceed bypercolating the juice through a compressed column of the exchanger witha bed depth for the exchanger of between 12-50 inches. Excessivepressure drops prohibit a higher bed depth, because of the extensiveresin expansion which occurs while the resin converts from the hydrogenform.

The effluent juice from the ion exchange treatment may exhibit a pHvalue of between 3.0 8.5 pH depending upon the original limesalt level,original alkalinity, temperature, flowrate and degree of resinexhaustion. The single figure of drawing illustrates a typical pH curvefor such ion exchange treatment.

Magnesium oxide is added to the juice so treated by ion exchange toobtain a final juice pH of between 8.0 9.0. Magnesium oxide addition iscontrolled according to the desired final pH allowing a retention timeof between to minutes for dissolving required magnesium oxide and pHequilibration.

A filtration step is usually desired after the magnesium oxide treatmentto remove excess reagent and other impurities before proceeding with theevaporation and crystallization.

The acidic functionality of the carboxylic type cation exchanger isusually exhausted after utilizing between 50-90% of its total exchangecapacity. The degree of resin utilization is primarily dependent upon pHand alkalinity of the juice to be treated and to a lesser degree uponthe contact time and operating temperature.

Regeneration of the exhausted ion exchange resin is then achievedthrough contact with a suitable strong mineral acid preferablyhydrochloric acid in the conventional well-established manner. Hence, asecond carbonation juice with a brix of l4Bx containing 0.300 g CaO per100 g dissolved dry substance and having a total alkalinity of 0.028(expressed as grams of CaO equivalent per 100 ml solution) is passedthrough a 36 inch column of a weak cation exchanger having carboxylicacid functionality. A flowrate of 80 resin bedvolumes per hour ismaintained at 85 until 300 bedvolumes of juice have passed through theion exchange column. Calcium ion concentration in the treated juice willaverage less than 0.03 grams of CaO equivalent per 100 grams ofdissolved dry substance. It requires less than one pound of magnesiumoxide per 100 cu. ft. of juice treated to restore juice alkalinity tothe desirable 0.023 gram CaO equivalent per 100 m1 juice and a pH ofabout 8.5. To regenerate the exhausted ion exchanger requires about 30gallons of 4% HCl per cu. ft. of resin used.

Example ll The conditions observed are the same as those outlined underExample I above except that the cation exchanger with carboxylic acidfunctionality is added continuously to a stream of the secondcarbonation juice, in the ratio of between 1/100 to 1/1000 depending onthe variable as outlined. A simple strainer or screen is used to achieveseparation of the juice from the resin particles after the appropriatecontact time.

EXAMPLE lll Conditions in this example are the same as under Examples lor II above except that after the ion exchange treatment the juice isforced through a \ertical column of granular magnesium oxide torealkalize the juice. The juice is allowed by this treatment toequilibrate to steady state which is a final pH of about 8.8.

We claim:

1. A process which comprises the steps of (a) treating sugar beet juice,after second carbonation, with the hydrogen form of a resinouscarboxylic type cation exchanger arranged in a column for the reductionof calcium ion in the juice, at a flowrate of between 20 and 200 resinbedvolumes per hour and at a temperature of 95 C and for a contact timeof between 20 seconds and 3 minutes; (b) realkalizing the so-treatedjuice with magnesium oxide to a pH between 7.5 and 9.5 and thereafter(c) filtering the realkalized juice to remove excess magnesium oxide andinsoluble impurities.

2. A process according to claim 1, wherein a portion of the insolubleseparated in 1(c) is recycled for realkalization.

3. A process according to claim 1, wherein realkalization isaccomplished by forcing the ion exchangetreated juice through a columnof granular magnesium oxide to a steady state point of alkalinity.

4. A continuous process which comprises the steps of treating a streamof sugar beet juice, after its second carbonation, with the hydrogenform of a resinous carboxylic type cation exchanger in a ratio requiredto maintain a pre-determined exchange rate in the ratio of from l/l00 toH000 and at a temperature of 7095 C. and for a contact time of between20 seconds and 3 minutes; separating the so-treated juice from thecation exchanger, re-alkalyzing the so-treated juice with magnesiumoxide to a pH between 7.5 and 9.5; and thereafter filtering there-alkalized juice to remove excess magnesium oxide and insolubleimpurities.

5. A process which comprises the steps of (a) treating sugar beetjuice,after second carbonation, with the hydrogen form of a resinouscarboxylic type cation exchanger arranged in a column for the reductionof calcium ion in the juice, at a flow rate of between 20 and 200 resinbedvolumes per hour and at a temperature of 7095 C and for a contacttime of between 20 seconds and three minutes; (b) re-alkalizing theso-treated juice with magnesium oxide to a pH of about 8.5; andthereafter (c) filtering the re-alkalized juice to remove excessmagnesium oxide and insoluble impurities.

UNTTED STATES PATENT OFFICE QENMQATE 0F CORECTIQN PATENT NO. 3, 887,391

DATED Jun 3 9 7 iNVENTORiS) KARLHEINZ W .RQSCHOENROCK et a1 It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below;

In the Title of Invention:

Before "SUGAR" Insert: OF

In claim t: line 6 "1/000" should read: l/lOOO fif Day 0 August1975[SEAL] AIIESI.

RUTH C. MASON C. MARSHALL DANN Arresting Officer ('ummi'xsimwr ofParents and Trademarks

1. A PROCESS WHICH COMPRISES THE STEPS OF (A) TREATING SUGAR BEET JUICE, AFTER SECOND CARBONATION, WITH THE HYDROGEN FORM OF A RESINOUS CARBOXYLIC TYPE CATION EXCHANGER ARRANGED IN A COLUMN FOR THE REDUCTION OF CALCIUM ION IN THE JUICE, AT A FLOWATE OF BETWEEN 20 AND 200 RESIN BEDVOLUMES PER HOUR AND AT A TEMPERATURE OF 70*-95*C AND FOR A CONTACT TIME OF BETWEEN 20 SECONDS AND 3 MINUTES; (B) REALKALIZING THE SOTR 9.5 AND THEREAFTER (C) FILTERING THE REALKALIZED JUICE TO REMOVE EXCESS MAGNESIUM OXIDE AND INSOLUBLE IMPURITIES.
 1. A process which comprises the steps of (a) treating sugar beet juice, after second carbonation, with the hydrogen form of a resinous carboxylic type cation exchanger arranged in a column for the reduction of calcium ion in the juice, at a flowrate of between 20 and 200 resin bedvolumes per hour and at a temperature of 70*-95* C and for a contact time of between 20 seconds and 3 minutes; (b) realkalizing the so-treated juice with magnesium oxide to a pH between 7.5 and 9.5 and thereafter (c) filtering the realkalized juice to remove excess magnesium oxide and insoluble impurities.
 2. A process according to claim 1, wherein a portion of the insoluble separated in 1(c) is recycled for realkalization.
 3. A process according to claim 1, wherein realkalization is accomplished by forcing the ion exchangetreated juice through a column of granular magnesium oxide to a steady state point of alkalinity.
 4. A continuous process which comprises the steps of treating a stream of sugar beet juice, after its second carbonation, with the hydrogen form of a resinous carboxylic type cation exchanger in a ratio required to maintain a pre-determined exchange rate in the ratio of from 1/100 to 1/000 and at a temperature of 70*-95* C. and for a contact time of between 20 seconds and 3 minutes; separating the so-treated juice from the cation exchanger, re-alkalyzing the so-treated juice with magnesium oxide to a pH between 7.5 and 9.5; and thereafter filtering the re-alkalized juice to remove excess magnesium oxide and insoluble impurities. 